1. Field of the Invention
The present invention relates to optical compensation films, polarizing plates and liquid crystal display devices.
2. Description of the Related Art
Optical compensation films produced by highly orienting a liquid crystal compound and fixing it have been recently developed for various uses such as optical compensation films and luminance enhanced films for liquid crystal display devices and optical compensation films for projection display apparatuses, and among them, growth as the optical compensation film for the liquid crystal display device is remarkable.
Typically, the liquid crystal display devices comprise polarizing plates and liquid crystal cells. In TFT liquid crystal display devices of TN mode which being most popular currently, optical compensation films are inserted between polarizing plates and the liquid crystal cells to realize liquid crystal display devices having a high display grade.
However, in this constitution, thickness of the liquid crystal display device itself becomes thick, and a request to make it thin could not be sufficiently satisfied.
For example, in the inventions described in Japanese Patent Application Laid-Open (JP-A) No. 07-191217 and European Patent Application Publication No. 0911656, problems in terms of view angles are solved without making the liquid crystal display device thick by directly using an optical compensation film obtained by applying an optically anisotropic layer formed from a discotic compound on a transparent support as a protection firm of the polarizing plate.
This way, the optical compensation film has been developed for the liquid crystal display device with the TN mode which is the current mainstream, but recently, demands for liquid crystal television have been increased, and it has been pointed out that there is a problem in response speed, e.g., a tailing phenomenon occurs in moving images.
In the inventions described in JP-A Nos. 09-211444 and 11-316378, the moving image is addressed by applying the optical compensation film having a layer composed of a liquid crystal compound to the liquid crystal display device with an OCB mode.
However, it is required for use in the liquid crystal televisions that high contrast is kept and reduced contrast due to a visual angle is lost. Thus, it has been difficult to obtain a proper front contrast by only controlling optical parameters known conventionally.
In recent years, it has been required for the liquid crystal televisions to consume a low electric power. Thus, it has been necessary to keep the high contrast and the wide view angle and further accomplish a high transmittance.
Therefore, various technologies for solving the above problems have been proposed, but it is an actual circumstance that no liquid crystal display device which keeps the high contrast and the wide view angle and further accomplishes the high transmittance is provided yet.